i just had the engine rebuilt rode 500 miles and changed the oil. should i change it again at another 500, 1000, or can i just go to the 3000 mark? i would feel a lot more comfortable chaning again at 500, but would like to know what you think.

Yes change again at another 500 miles. Switch to oil of your choice at this point i recommend amsoil(at your current mileage of 500 most of engine break in should have already occured perticuarly if u werent babying it and switching to a synthetic wont impead break in enough to matter). After the 1000 mile mark change oil at your preferred change interval.